Akito's mother. Koharu died giving birth to Akito, an event which had a serious negative effect on the relationship between Akito, Natsumi, and Fuyuki. Although she has been dead for more than 10 years by the beginning of the series: she "appears" sporadically throughout the manga in memories, photos, and flashbacks. Her most important appearance is in Volume Eight when Akito has a near-death experience; Koharu appears to him as a stranger and tells him that he is too young to die and that he can be strong. When Akito realizes that she is his mother, Koharu repeats Sana's words from Volume One, telling Akito that she loves him and that he must live for both of them.

Koharu was apparently a troublemaker (or at least "wild") in her younger years, along with Fuyuki. In the manga, she is said to have once been a Yankee.

(Source: Wikipedia)